Jack up the truck so the wheels are off the ground and support it with jackstands under the frame.
Remove the shock/spring assembly.
You might want to simply take the shock/spring assemblies to a shop that has a bench-mounted spring compressor and let them do the disassembly/reassembly with the new shocks. Using external "j-hook" spring compressors can be hazardous, as the compressed springs store a bunch of energy. If one slips and comes loose, it instantly becomes a potentially lethal missle. Otherwise:
Compress the spring, maintaining equal pressure on each of the compressor elements. Compress it only enough to take the tension off the spring seats. Remove the top nut on the shock rod. Disassemble the shock/spring units and reassemble using the new shocks. Take care to reassemble with the lower spring seat right-side up. Replace the spring, top spring seat and bushings. Replace the shock rod nut, washer and any other hardware you took off. When the shock rod nut is tight, gradually and equally release the spring compressors, being careful to position the spring coils properly in both the top and bottom spring seats.
Reinstall the shock/spring units. You shouldn't need to re-do the wheel alignment, as you haven't disturbed anything that would change it.
An air impact wrench is a major help in doing this job. The dodgy part of the job is compressing the springs and disassembling the spring/shock units. Otherwise, it's pretty straightforward.
Good luck.
